Patent of the Month – Monocentric Lens
Editor | On 18, Feb 2018
If I was a betting man, I’d say that this month’s patent of the month had the smell of TRIZ about it. US9,860,443 was granted to a trio of inventors at the University of California. Two of them have Russian-sounding names. The real giveaway, however, seems to be their background description for the invention. Which goes something like this:
Imagers that require the combination of wide field of view, high angular resolution and large light collection present difficult challenges in optical system design. For example, geometric lens aberrations increase with aperture diameter, numerical aperture and field of view, and scale linearly with focal length. This means that for a sufficiently short focal length, it is possible to find near diffraction-limited wide angle lens designs, including lenses mass-produced for cellphone imagers. However, obtaining high angular resolution (for a fixed sensor pixel pitch) requires a long focal length for magnification, as well as a large numerical aperture to maintain resolution and image brightness. This combination is difficult to provide over a wide angle range. Conventional lens designs for longer focal length wide-angle lenses represent a tradeoff between competing factors of light collection, volume, and angular resolution. For example, conventional reverse-telephoto and “fisheye” lenses provide extremely limited light collection compared to their large clear aperture and overall volume. However, the problem can go beyond the lens itself. For example, solving this lens design only leads to a secondary design constraint, in that the total resolution of such wide angle lenses may easily exceed 100 Megapixels. This is beyond the current spatial resolution and communications bandwidth of a single cost-effective sensor, e.g., especially for video output at 30 frames per second or more.
They don’t go quite to the extent of using the word, ‘contradiction’, but, nevertheless, the story is one of multiple iron-triangle conflicts and trade-offs, and an industry that conventionally designs through them by compromise. The inventors also didn’t quite go so far as including any Bubble Maps. If they had, I think one of them would have looked like this:
Which we can then use to compare with what the inventors actually did to create their invention…
What is claimed is:
- An optical imaging system, comprising: a monocentric optical imaging module including one or more optical elements having concentric surfaces to collect light and form an image on a curved image surface; one or more curved and tapered optical waveguide bundles each comprising a plurality of optical waveguides that are optically coupled to the monocentric optical imaging module at different locations to receive different portions of the collected light at the curved image surface, respectively, wherein each optical waveguide bundle includes an input optical waveguide bundle facet to receive light from the curved image surface and an output optical waveguide facet to output light; one or more imaging sensors to receive light from the one or more curved and tapered optical waveguide bundles and to detect the received light, the one or more imaging sensors configured to produce a representation of the image on the curved image surface of the monocentric optical imaging module; and a textured surface structure over the input optical waveguide facet associated with optical waveguides of each curved and tapered optical waveguide bundle to enhance optical coupling from the curved imaging surface into the plurality of optical waveguides, wherein at least one of the one or more curved and tapered optical waveguide bundles has a curved input facet, and principal rays of the monocentric optical imaging module input to the plurality of optical waveguides are substantially aligned with an axis of a corresponding optical waveguide to facilitate propagation of light through each optical waveguide in producing a substantially uniform divergence of the light that is output from each of the one or more curved and tapered optical waveguide bundles.
Did you spot the read-across?
Principles 14 (Curvature), 17 (Another Dimension – ‘tapered’), 3 (Local Quality – textured surface), 35 (Parameter Change – optical waveguide…), 5 (Merging – …bundles…), 1 (Segmentation – …multiple).
Easy when you know how.